The present invention relates to a pressure differential valve.
Valves of this type are used in order to obtain a constant gradient of pressure between an inlet pressure and an outlet pressure. A pressure differential valve of this type is disclsed in the German patent application No. 36 36 409.6 which corresponds to pending U.S. application Ser. No. 112,635 filed Oct. 22, 1987 for Pressure Control Valve. This U.S. Application is assigned to the assignee of this application. In that valve, a differential piston whose larger pressurized surface is associated with the outlet pressure is displaced in opposition to the force of a preloading spring in a manner such that a spring-loaded ball seat valve is brought into a closed position.
A valve design of this type includes a multitude of component parts that are expensive to produce, has a great overall length and a high weight. The change-over point of this valve is determined by the pressure prevailing in the outlet so that, as a result, a considerable volume of fluid must be conveyed by way of the valve overflow cup during pressure reduction until the differential piston returns to its initial position and thereby establishes a free flow from inlet to outlet.